After years of delay, Mexico could open up its vast shale oil fields to U.S. drillers as soon as next year, the Mexican secretary of energy said Friday.

Pedro Joaquin Coldwell, speaking to energy executives, attorneys and academics at Rice University, said that the long-suspended auctions for northern Mexico’s shale fields could reopen after the first quarter of 2017.

“Everything will be ready by March,” he said.

The fields could provide Houston oil companies with nearby and ready-made opportunities for expansion. Much of it is essentially an extension of the Eagle Ford reservoir, which stretches from central Texas and into Mexico. Local companies, familiar with the geology and now experts in hydraulic fracturing, could be first in line to develop the fields.

Mexico, in the middle of sweeping energy reform, is holding auctions to sell the rights for private companies to drill in its untapped oil fields. The country has gathered more than $22 billion in private sector commitments so far, on projects ranging from oil drilling to pipelines to power plants.

But the state suspended bids for shale field exploration when oil prices crashed two years ago.

“We thought industry wouldn’t be interested,” Coldwell told the roughly 100 people at the event.

The country also lacked environmental rules to regulate hydraulic fracturing and the pipelines necessary to transport natural gas, a byproduct of oil drilling.

Companies recently told Mexico they were interested again in a shale auction, Coldwell said, and environmental regulations are expected to be ready by March.

Mexico nationalized its energy industry and kicked foreign oil drillers out of the country more than 70 years ago. But in 2013, with soaring electricity rates and plummeting oil and gas production, Mexican lawmakers passed a sweeping set of energy reform laws, which opened the country to widespread private investment for the first time since 1938.

The national oil company, Petróleos Mexicanos, known as Pemex, kept some of the country’s proven reserves to drill in the future. Mexico then started auctioning blocks of oil land that Pemex wasn’t holding.

The first three auctions mostly sold rights to shallow water in the Gulf of Mexico. The next auction, this December, is for 10 deep-water fields. Shale lots could follow.

More than three-quarters of the prospective resources are in deep water or shale. To access such reserves, the country needs drilling technology and financial resources “not now available in Mexico,” Coldwell said.

The deep-water sections are considered prized because they are near existing offshore drilling rigs along the U.S. border in the Gulf; oil companies already know how to find oil there and how to tie production into existing pipelines.

Some, however, are skeptical that oil companies will jump into Mexican shale. It looks to have more natural gas than oil, which makes it less valuable. Security might be an issue. Water is hard to find. And there are few pipelines, storage tanks or other pieces of the supply chain.

Still, analysts said, the Mexican shale fields are huge, with untold volumes of oil and gas.

“There’s a lot of potential,” said Pablo Medina, an analyst at the energy research firm Wood Mackenzie.